First, we may want to start out with what it was not. It was not an inland hurricane, although it may have felt like one. A hurricane is tropical in nature, this system that we experienced was convective.

It was not a large tornado. Although there were several small tornadoes embedded within the widespread damaging winds.

However, this was not your typical derecho. Often on these types of systems in the northern hemisphere, a bookend vortex, or comma head develops on the north side of the system. The comma head usually acts like a large paddle wheel on a boat and helps to focus strong winds in behind the bowing squall line. A large portion of the damaging winds occurred on the southwest and southern end of the comma head.

Although it is still under study, it appears that at least some of the tornadoes in this case occurred with the comma head. This is not unusual, in fact research work in the 1980s documented a case of a derecho that moved through central Illinois in which tornadoes were associated with the comma head.

The system that moved through on May 8 had an unusually large bookend vortex. Numerical simulations completed in the early 1990s and some observational studies documented commahead vortexes were on average 12 nm in diameter. The comma head on the May 8th storm was 30 to 40 nm in diameter. In fact, this is the largest bookend vortex that some experts have seen in their careers. This will be the subject of more in-depth research for years to come.

Overview: A widespread damaging wind event with isolated embedded tornadoes occurred in southern Illinois and parts of southeast Missouri on Friday, May 8.

Peak wind gusts were measured over 80 mph at Marion and Carbondale, IL. The peak gust recorded by the automated system at the Carbondale airport was 81 mph before the system failed. An observer at the airport visually observed a separate anemometer located on the rooftop reach 106 mph. The automated system measured a sustained wind of 68 mph before failing.

Extensive tree and power line damage occurred in the Murphysboro, Carbondale, and Marion areas of southern Illinois and Perry and Bollinger Counties of southeast Missouri. Numerous structures were damaged in the Marion, Carbondale, and Murphysboro areas. While injuries were reported, an approximate count was not available. One fatality occurred in Jackson County when a tree fell on a home, causing an elderly man to fall to his death.

State disaster declarations were granted for Jackson, Williamson, and Franklin Counties. Curfews and states of emergency were declared locally.

The Williamson County airport near Marion reported a peak gust of 86 mph. There was extensive damage at the airport, including hangar buildings.

Wind damage extended eastward into the Harrisburg area (Saline County). The system weakened before exiting southern Illinois.

Damage surveys were conducted on Saturday, Monday, and Tuesday.

The damaging winds were associated with the "comma head" of a bow echo. The comma head maintained unusually strong intensity after the bow echo began to dissipate.

Radar Images:

Radar image of the "eye" feature, which developed in the center of the comma head. The "eye" is visible as the light blue center surrounded by heavier echoes. This feature is located just north of Carbondale (near center of photo and due east of Farmington, MO). Image taken at 1:28 P.M. CDT.

Radar image of the "eye-like" center, taken at 12:57 P.M. The center was over Murphysboro in this image.

*** 2 FATAL *** MISSOURI HIGHWAY PATROL REPORTED A TREE
FELL ON A CAR...THE CAR CAUGHT ON FIRE AND 2 PEOPLE
INSIDE WERE KILLED. LOCATION WAS ONE MILE SOUTH OF POPLAR
BLUFF ON HIGHWAY 53. TIME APPROXIMATE.

NUMEROUS TREES AND POWER LINES DOWN IN HARRISBURG,
ELDORADO, CARRIER MILLS, GALATIA AND RALEIGH. TREE FELL
ON HOUSE AND STRUCK GAS METER...GAS LEAKING IN GALATIA.
ROOF BLOWN OFF BUILDING IN CARRIER MILLS AND STRUCK GAS
METER...GAS LEAKING. TREE FELL ON PROPANE TANK IN
STONEFORT...GAS LEAKING. SEMI BLOWN OVER ON IL 34 NEAR
HARRISBURG AIRPORT. DEPUTY REPORTED ESTIMATED 90 MPH
WINDS NEAR HARCO WITH DEBRIS IN THE AIR. IL 34 CLOSED IN
NUMEROUS LOCATIONS.PORTIONS OF US45 CLOSED NEAR LEDFORD.

* DISCUSSION/DAMAGE - DOZENS OF LARGE TREES SNAPPED AND UPROOTED.
STRUCTURAL DAMAGE TO TWO BARNS WITH METAL ROOF PANELS AND METAL
DOORS BLOWN OFF. SHINGLES BLOWN OFF SEVERAL HOMES. SEVERAL POWER
POLES BLOWN OVER, ONE SNAPPED OFF. MOST OF TORNADO PATH WAS THROUGH
OPEN FIELDS.

* DISCUSSION/DAMAGE... VIDEOTAPED BY PERSON AT THE PERRYVILLE
AIRPORT AND SHOWN ON LOCAL MEDIA OUTLET. PATH VISIBLE IN WHEAT
FIELD ALONG COUNTY ROAD 934. DOZENS OF TREES DOWN NEAR THE
PATH...APPARENTLY DUE TO INFLOW WINDS. EYEWITNESS ACCOUNTS.

SURVEYORS...HOOPER/BLANCHARD

PHOTOS
Straight-line winds along Route 13 in Marion/Carbondale area:

Numerous signs were damaged...

Many towers were bent...

Signs were blown out...

This gas station's canopy over the pumps was levelled...

Tree on house in Murphysboro...

Tree on house at Galatia, IL (photo from Saline Co. 911):

One of many utility poles down on Route 13 between Marion and Carbondale:

Traffic lights were out at major intersections along Route 13:

Mobile home heavily damaged in rural northeast Jackson County:

Trees down across Interstate 57 near the 60-mile marker in far northern Williamson County (photo courtesy Stephen Hagan):

Home under construction blown down in southern Williamson County, south of Marion:

Map

There have been windstorms similar to this in the past. On July 22, 1980, a similar windstorm moved through the region with damaging winds over 100 mph.This derecho was actually the storm system that sparked the study on these types of windstorms and where the term "derecho" originated.

Below is a sketch of the location of the leading edge of the derecho. thanks for Bob Johns